This is a continuation of ongoing work to understand the genetics and pathogenesis of pectus excavatum in Lemur variegatrus, the black and white ruffed lemur. The condition appears to be inherited as an autosomal dominant and is, at times, expressed as flat chest. It is not manifest at birth but develops in some individuals towards the end of their first year of life. A few lethal skeletal anomalies have also occurred in this pedigree but do not appear to have a direct relationship to pectus. In addition, severe hemosiderosis, occasional hemochromatosis, and hepatomas have been observed in this colony. These are studied through selective breeding.